Make longer and thinner stone cat (7)
I believe the answer is:
stretch
'make longer' is the definition.
(stretching is a kind of making longer)
'thinner stone cat' is the wordplay.
'thinner stone' becomes 'st' (abbreviation. I am not sure about the 'thinner' bit.).
'cat' becomes 'retch' (synonyms).
'st'+'retch'='STRETCH'
'and' is the link.
Can you help me to learn more?
(Other definitions for stretch that I've seen before include "Make demands on; continuous expanse" , "Lengthen - time in jail" , "Tax" , "how much time one's been given" , "Exercise - period" .)