Male rowers, dreadful moaners (7)
I believe the answer is:
oarsmen
'male rowers' is the definition.
(men rowing with oars)
'dreadful moaners' is the wordplay.
'dreadful' indicates an anagram.
'moaners' with letters rearranged gives 'OARSMEN'.
(Other definitions for oarsmen that I've seen before include "Male propellers of boats" , "Strokes" , "They propel a boat manually" , "People in boats" , "Rowing types" .)