Part of aircraft soldiers modify (6)
I believe the answer is:
tailor
'modify' is the definition.
(thesaurus)
'part of aircraft soldiers' is the wordplay.
'part of aircraft' becomes 'tail' (I can't justify this - if you can you should believe this answer much more).
'soldiers' becomes 'OR' (Other Ranks).
'tail'+'or'='TAILOR'
Can you help me to learn more?
(Other definitions for tailor that I've seen before include "person before soldier and sailor in list" , "Fashion" , "Fit" , "Maker of men's suits" , "One makes suits etc. to measure" .)