Crew of terrible moaners (7)
I believe the answer is:
oarsmen
'crew' is the definition.
(I've seen this before)
'terrible moaners' is the wordplay.
'terrible' indicates anagramming the letters.
'moaners' with letters rearranged gives 'OARSMEN'.
'of' is the link.
(Other definitions for oarsmen that I've seen before include "possibly eight in a row" , "They propel boats manually" , "A sermon about rowers" , "Scullers" , "Male rowers" .)