Man quietly being apprehended by thug gets aid (4,3)
I believe the answer is:
help out
'aid' is the definition.
(thesaurus)
'man quietly being apprehended by thug' is the wordplay.
'man' becomes 'he'.
'quietly' becomes 'p' (p for piano and quiet).
'being apprehended by' indicates putting letters inside (I've seen this in other clues).
'thug' becomes 'lout'.
'p' placed into 'lout' is 'lpout'.
'he'+'lpout'='HELP OUT'
'gets' is the link.
(Other definitions for help out that I've seen before include "Assist as in a crisis - to leave house?" , "Give assistance" , "Lend a hand" .)