Solved while enroute to Disneyland in LA.
ACROSS
1 Poor husband besieged by poet, a boastful person (8) BLOWHARD {B{LOW}{H}ARD}
5 Help to secure new permit (6) ASSENT {ASSE{N}T}
10 Glossy fabric in stores at India (5) SATIN [T]
11 What a fisherman might do to keep in touch? (4,1,4) DROP A LINE [DD]
12 Bad time to enter perfect precision marching unit (5,4) DRILL TEAM {DR{ILL}{T}EAM}
13 Incompetent, unresponsive Republican becomes President (5) INEPT INE(-r+p)PT
14 Female is about to ruin brutes (6) FIENDS {F}{I{END}S}
15 Jointly presents expenses to maintain house (2-5) CO-HOSTS {CO{HO}STS}
18 Having fever, weary one dropped the boards (7) THEATRE {T
20 Wander around emporium gutted in fire (6) REMOVE {R{E
22 Worthless, crazy son kicked out (5) INANE IN
24 Very obvious! Compose a letter to win heart of mesmerizing gal easily (4,5) WRIT LARGE {WRIT{LA{
25 Yank – a fellow with perfect grimace (4,1,4) PULL A FACE {PULL}{A}{F}{ACE}
26 Hallucinatory experience on Ecstasy? Nonsense (5) TRIPE {TRIP}{E}
27 British ballet dancer to prosper (6) DOWELL {DO}{WELL}
28 Writer's point? Be silent perhaps (5,3) STEEL NIB*
DOWN
1 Close to where a nurse might be dropping daughter (6) BESIDE BE
2 Abuse of nicotine keeps husband in a precarious situation (2,4,3) ON THIN ICE {NICOTINE}* over {H}
3 . A reason for dismissal of student involved in throwing the party (8,3,4) HANDLING THE BALL {HAND{L}ING}{BALL}
4 Right to change clothes (7) REDRESS [DD]
6 It seems hotel's prepared to include roast dish from Europe (7,8) SPANISH OMELETTE {IT+SEEMS+HOTEL}* over {PAN}
7 Refugee in complex I lease (5) EXILE [T]
8 Study time! Get up suppressing worry (8) TREATISE {T}{R{EAT}ISE}
9 Huge clown entertains son (6) COSMIC {CO{S}MIC}
16 Queen left England overwhelmed by gesture (9) SOVEREIGN {S{OVER}{E}IGN}
17 Son made a mistake, dispossessed (8) STRIPPED {S}{TRIPPED}
19 Envelope from model leaving Antwerp sadly (6) ENWRAP AN
20 Plan to wear torn garments (7) RAIMENT {R{AIM}ENT}
21 Echo effect always found in Rhythm & Blues (6) REVERB {EVER} in {R&B}
23 Authorise construction of wall around Mexico at last (5) ALLOW {WALL}* over {
Reference List
Husband = H, New = N, Republican = R, President = P, Female = F, House = HO, Fellow = F, Ecstasy = E, Daughter = D, Student = L, Time = T, Son = S, England = E, Model = T,
