Grill composer missing the last prompt (8)
I believe the answer is:
barbecue
'grill composer' is the definition.
'barbecue' can be an answer for 'grill' (barbecuing is a kind of grilling). I'm not sure about the 'composer' bit.
'missing the last prompt' is the wordplay.
'missing the last' becomes 'barbe' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'prompt' becomes 'cue' (synonyms).
'barbe'+'cue'='BARBECUE'
Can you help me to learn more?
(Other definitions for barbecue that I've seen before include "cook burgers, say" , "Portable grill for cooking outdoors" , "Outdoor eating occasion" , "Grill over an open fire" , "A picnic with grilled meats" .)