Pretend not to care about stage work that's pretty incomprehensible (4,4,2,3)
I believe the answer is:
play hard to get
'pretend not to care about' is the definition.
(as in playing hard to get romantically)
'stage work that's pretty incomprehensible' is the wordplay.
I cannot really see how this works, but
'work' could be 'hard' (hard work is a kind of work) and 'hard' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for play hard to get that I've seen before include "shown to be tantalising" , "Gain by appearing unwilling to co-operate" , "Seem reluctant to come across" , "Act coy, hoping to increase one's appeal" , "Pretend to be indifferent" .)