F-feeble fire (5)
I believe the answer is:
flame
'fire' is the definition.
(synonyms)
'f-feeble' is the wordplay.
'feeble' becomes 'lame' (lame can mean feeble or pathetic).
'f'+'lame'='FLAME'
(Other definitions for flame that I've seen before include "Evidence of fire" , "strong red" , "Burning gas from fire" , "Orange-red colour" , "Brilliant orange-red" .)