This time I sit with Fatty (7)
I believe the answer is:
adipose
'fatty' is the definition.
(synonyms)
'this time i sit' is the wordplay.
'this time' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'sit' becomes 'pose' (synonyms).
'ad'+'i'+'pose'='ADIPOSE'
'with' is the link.
(Other definitions for adipose that I've seen before include "Relating to fat" , "Composed of animal fat" , "Of tissue, fatty in substance" , "Is a dope fat?" , "Containing fat" .)