Thick bagel firstly with salmon? (6)
I believe the answer is:
oafish
'thick' is the definition.
(thesaurus)
'bagel firstly with salmon?' is the wordplay.
'bagel' becomes 'O' (bagel can mean a score of zero in tennis).
'firstly' becomes 'a' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'salmon?' becomes 'fish' (salmon is a kind of fish).
'o'+'a'+'fish'='OAFISH'
Can you help me to learn more?
(Other definitions for oafish that I've seen before include "Like a lout" , "Boorish, clumsy" , "lacking elegance?" , "Doltish" , "Bone-headed" .)