ACROSS
8 - Good word will tone one commander disorganised (14) - RECOMMENDATION (tone+i+commander)*
9 - Note our man following the Supreme Court method (6) - SCHEME {SC}{HE}{ME}
10 - Weight problem (8) - NUISANCE [CD?] Why weight?
11 - Out of date order covers the well lease (8) - OBSOLETE {OB{SO}{LET}E}
13 - Shrug off the leaders in Ghana not observing rules easily (6) - IGNORE {I}{G}{N}{O}{R}{E}
14 - New currency (6) - TENDER [DD]
16 - Content user biased in this country (6) - SERBIA [T]
21 - Note an unopened fence around the coal site (8) - EMINENCE {fE{MINE}NCE}
23 - Telephone man has a door sign to manifest his calling (4,4) - BELL PUSH {BELL} {PUSH} (Addendum BELL PULL {BELL} {PULL} - See comments)
24 - Nebraska Indians (6) - OMAHAS [GK]
26 - Divided the outline of the graph (7,7) - SCATTER DIAGRAM {SCATTER} {DIAGRAM}
1 - It flies behind the building block when thrown as a missile (8) - BRICKBAT {BRICK}{BAT}
2 - Part of a plot in an Israeli port (4) - ACRE [DD]
3 - Hold back an evil spirit in the meddle regularly (6) - IMPEDE {IMP{mEdDlE}
4 - A curve in a river (7) - MEANDER [E]
5 - To improve it, I have to use the preservative (8) - ADDITIVE {ADD}{IT}{I'VE}
6 - Possible to achieve a target in front with a characteristic alien abbot not an American man (10) - ATTAINABLE {A}{T}{TAINABLEbo*}
7 - Regularly stoics cheer this world cup sport (6) - SOCCER {StOiCs ChEeR}
12 - Make less visible (10) - OBNUBILATE [E] Another new obscure word for me.
15 - Killed the senior manager out at tea-time in Germany (8) - EXECUTED {EXECUTivE}{D}
17 - Welcomes the current lot of mails distributed (8) - ACCLAIMS {AC}{C}{LAIMS*}
18 - Keep apart (7) - METHODS ?(Addendum - SECLUDE [E] - See comments)
20 - Some children cheerfully get wet (6) - DRENCH [T]
22 - Weather map line (6) - ISOBAR [E]