Heart shown by men, but not head, in second performance (6)
I believe the answer is:
encore
'performance' is the definition.
(I have seen 'extra performance' mean 'encore' so perhaps 'performance' could also mean 'encore')
'heart shown by men but not head in second' is the wordplay.
'heart' becomes 'core' (synonyms).
'shown by' means one lot of letters go next to another.
'men' becomes 'se' (I have seen 'Spanish men ' mean 'se' so perhaps 'men' could also mean 'se').
'but not head' means to remove the first letter.
'in second' becomes 'n' (ond letter of 'in').
'se' with its first letter taken away is 'e'.
'e'+'n'='en'
'core' after 'en' is 'ENCORE'.
(Other definitions for encore that I've seen before include "extra performance" , "Call for repetition" , "Bis!" , "Play it again, Sam?" , "Repetition of performance" .)