Turned grey, losing heart with assessment (7)
I believe the answer is:
gyrated
'turned' is the definition.
(gyrating is a kind of turning)
'grey losing heart with assessment' is the wordplay.
'losing heart' says to hollow out the word (remove centre letters).
'with assessment' becomes 'rated' (a rating is an assessment).
'grey' with its middle taken out is 'gy'.
'gy'+'rated'='GYRATED'
(Other definitions for gyrated that I've seen before include "Writhed" , "What Turner did" , "What whirling dervishes did" , "did turns" .)