Make defensive move as learner in class (6)
I believe the answer is:
castle
'make defensive move' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'learner in class' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'in' indicates putting letters inside.
'class' becomes 'caste' (type of social class).
'l' placed inside 'caste' is 'CASTLE'.
'as' is the link.
Can you help me to learn more?
(Other definitions for castle that I've seen before include "''An Englishman's home is his . . .''" , "Stronghold - rook" , "old building?" , "Chess piece and fortified building" , "Keep" .)