Play with reserve, in accordance with law (8)
I believe the answer is:
underact
'play' is the definition.
(underacting is a kind of playing)
'reserve in accordance with law' is the wordplay.
'reserve in accordance' becomes 'under' (I can't explain this - if you can you should believe this answer much more).
'with' says to put letters next to each other.
'law' becomes 'act' (I've seen this before).
'under'+'act'='UNDERACT'
'with' acts as a link.
Can you help me to learn more?
(Other definitions for underact that I've seen before include "put little into role" , "Deliver role in a restrained manner" , "Of thespian, perform with excessive restraint" , "Minimise part played" , "Perform impassively" .)