Support is coming through. Don't give in (6)
I believe the answer is:
resist
'don't give in' is the definition.
(I've seen this before)
'support is coming through' is the wordplay.
'support' becomes 'rest' (e.g. a shoulder rest is a support for shoulder).
'coming through' indicates putting letters inside.
'rest' placed around 'is' is 'RESIST'.
(Other definitions for resist that I've seen before include "Withstand, oppose" , "Endure" , "Refuse to give in to" , "Stand up to, fight against" , "Take stand against, oppose" .)