Mould to bung round a vessel for firing (7)
I believe the answer is:
gunboat
'vessel for firing' is the definition.
I can't tell whether this definition defines the answer.
'mould to bung round a' is the wordplay.
'mould' indicates anagramming the letters.
'round' is an insertion indicator.
'to'+'bung'='tobung'
'tobung' anagrammed gives 'gunbot'.
'gunbot' going around 'a' is 'GUNBOAT'.
Can you help me to learn more?
(Other definitions for gunboat that I've seen before include "Small armed vessel" , "Military vessel" , "Small military ship" , "Vessel (involved in a type of diplomacy?)" , "Not a bug (anag)" .)