Army caterer admitting Blumenthal's starter is nicer (7)
I believe the answer is:
subtler
'nicer' is the definition.
Both the definition and answer are comparative adjectives. Perhaps you can see an association between them that I don't see?
'army caterer admitting blumenthal's starter' is the wordplay.
'army caterer' becomes 'sutler' (I am not sure about this - if you are sure you should believe this answer much more).
'admitting' means one lot of letters goes inside another (admit can mean to welcome in or accept).
'starter' indicates taking the first letters.
The initial letter of 'blumenthal' is 'b'.
'sutler' enclosing 'b' is 'SUBTLER'.
'is' is the link.
Can you help me to learn more?
(Other definitions for subtler that I've seen before include "More able to make fine distinctions" , "More delicate or understated" .)