Iron is moulded round large cut (7)
I believe the answer is:
sirloin
'cut' is the definition.
(I know that sirloin is a type of cut of beef)
'iron is moulded round large' is the wordplay.
'moulded' is an anagram indicator.
'round' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'iron'+'is'='ironis'
'ironis' anagrammed gives 'siroin'.
'siroin' placed around 'l' is 'SIRLOIN'.
(Other definitions for sirloin that I've seen before include "(Knighted?) cut of meat" , "Type of steak" , "Prime cut of beef" , "Good cut of beef" , "Choice cut of beef" .)