Real SOS at sea, when unable to propel boat? (7)
I believe the answer is:
oarless
'unable to propel boat?' is the definition.
'real sos at sea' is the wordplay.
'at sea' indicates an anagram.
'real'+'sos'='realsos'
'realsos' with letters rearranged gives 'OARLESS'.
'when' acts as a link.
(Other definitions for oarless that I've seen before include "Lacking a means of moving" , "like the coxswain" , "without a paddle" , "Unable to row" , "ill-equipped for 35 [REHATTAS]" .)