Apply pressure to withdraw from specialist (5)
I believe the answer is:
exert
'apply' is the definition.
(exerting is a kind of applying)
'pressure to withdraw from specialist' is the wordplay.
I cannot quite see how this works, but
'from' could be 'ex' ('from' in Latin) and 'ex' 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 exert that I've seen before include "Employ" , "Bring into operation" , "Bring into play, wield" , "Expend" , "Strain" .)