Long-suffering man or woman that is not heartless (7)
I believe the answer is:
patient
'long-suffering' is the definition.
(similar in meaning)
'man or woman that is not heartless' is the wordplay.
'man or woman' becomes 'Pat' (unisex name - Patrick or Patricia).
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'heartless' suggests removing the centre.
'not' with its middle taken out is 'nt'.
'pat'+'ie'+'nt'='PATIENT'
(Other definitions for patient that I've seen before include "Forgiving" , "Long-suffering - one under treatment" , "case for treatment" , "one receiving medical treatment" , "Cool" .)