Little Malcolm is the smallest (7)
I believe the answer is:
minimal
'the smallest' is the definition.
(I've seen this before)
'little malcolm' is the wordplay.
'little' becomes 'mini'.
'malcolm' becomes 'mal' (I can't justify this - if you can you should give a lot more credence to this answer).
'mini'+'mal'='MINIMAL'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for minimal that I've seen before include "Very little" , "barely worth considering" , "Of a smallest amount" , "Token" , "Of the least possible size" .)