Roar half-heartedly — for the next clue? (5)
I believe the answer is:
below
'the next clue?' is the definition.
(the clue below)
'roar half-heartedly' is the wordplay.
'roar' becomes 'bellow' (synonyms).
'half' suggests halving the letters.
'heartedly' becomes 'ow' (I can't explain this - if you can you should give a lot more credence to this answer).
'bellow' halved is 'bel'.
'bel'+'ow'='BELOW'
'for' is the link.
(Other definitions for below that I've seen before include "Not worthy of" , "Lower than" , "on earth" , "Underneath" , "second-rate" .)