Just back to pinch right cheek (5)
I believe the answer is:
nerve
'cheek' is the definition.
(I know that cheek can be written as nerve)
'just back to pinch right' is the wordplay.
'just' becomes 'even'.
'back' is a reversal indicator.
'to pinch' means one lot of letters goes inside another.
'right' becomes 'r' (common abbreviation).
'even' reversed gives 'neve'.
'neve' going around 'r' is 'NERVE'.
(Other definitions for nerve that I've seen before include "Cord that carries instructions from brain to body" , "Sauce" , "Courage - cheek" , "Impudence (colloq.)" , "Courage to carry on" .)