He serves, with heavier heart, to give a tangled tale (5)
I believe the answer is:
valet
'he serves' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'heavier heart to give a tangled tale' is the wordplay.
'heart' says to take the centre.
'to give' is a charade indicator (letters next to each other).
'a tangled' indicates anagramming the letters.
The middle of 'heavier' is 'v'.
'tale' with letters rearranged gives 'alet'.
'v'+'alet'='VALET'
'with' is the link.
Can you help me to learn more?
(Other definitions for valet that I've seen before include "Male servant" , "Personal serving man" , "Personal male assistant" , "Man's servant" , "Clean (a car); attendant" .)