Having life with cracking single partner - quite the reverse (8)
I believe the answer is:
animated
'having life' is the definition.
(animated can mean alive)
'with cracking single partner quite the reverse' is the wordplay.
'with' indicates putting letters inside.
'cracking' indicates anagramming the letters.
'single' becomes 'I' (one).
'partner' becomes 'n'.
'quite the reverse' becomes 'amated' (I can't justify this - if you can you should give a lot more credence to this answer).
'i'+'n'='in'
'in' anagrammed gives 'ni'.
'ni' placed within 'amated' is 'ANIMATED'.
(Other definitions for animated that I've seen before include "Lively - like cartoon films" , "Full of excitement, lively" , "put in spirit" , "Enlivened (like a cartoon film)" , "Lively in diamante" .)