Bring up forecast for fantastic captain (4)
I believe the answer is:
nemo
'fantastic captain' is the definition.
(character from 20,000 Leagues Under the Seas)
'bring up forecast' is the wordplay.
'bring up' is a reversal indicator.
'forecast' becomes 'omen' (synonyms).
'omen' written backwards gives 'NEMO'.
'for' acts as a link.
(Other definitions for nemo that I've seen before include "- me impune lacessit (motto of Scotland)" , "Jules Verne's submarine captain" , "Captain of the Nautilus" , "Captain brought to book" , "Jules Verne captain" .)