Construction kit: something to resort to on retiring (7)
I believe the answer is:
meccano
'construction kit' is the definition.
(toy brand)
'something to resort to on retiring' is the wordplay.
'something to resort to' becomes 'mecca' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'retiring' shows that the letters should be reversed in order.
'on' backwards is 'no'.
'mecca'+'no'='MECCANO'
Can you help me to learn more?
(Other definitions for meccano that I've seen before include "Metal model construction set" , "It's for kids' building" , "constructive materials" , "Children's nuts and bolts kit" , "Set of metal components for making toy models" .)