Cat visits old church a great deal (6)
I believe the answer is:
'cat visits' is the definition.
'ocelot' can be an answer for 'cat' (I've seen this before). I'm not certain of the 'visits' bit.
'old church a great deal' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'church' becomes 'CE' (abbreviation for Church of England).
'a great deal' becomes 'lot' ('lot' can be a synonym of 'great deal').
Can you help me to learn more?
(Other definitions for ocelot that I've seen before include "American cat, like a small leopard" , "Small leopardlike cat" , "Leopard-like cat of S America" , "Wild cat of the Americas" , "Feline of South and Central America" .)