Formed of units mostly produced from a mould ~n right? (7)
I believe the answer is:
modular
'formed of units mostly produced from a' is the definition.
I can't tell whether this definition defines the answer.
'mould n right?' is the wordplay.
I cannot really understand how this works, but
an anagram of 'mould' is 'modul' which is present in the answer.
'right?' could be 'ar' (I've seen this in other clues) and 'ar' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for modular that I've seen before include "Made of units" , "Built from separate units" , "Made from detachable pieces" , "in several parts" .)