Cause to give up one's occupation (5)
I believe the answer is:
evict
'cause' is the definition.
Although both the answer and definition are verbs in their base form, I can't see how one could define the other.
'up one's occupation' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'one's' becomes 'ive' ('one has' can mean 'I have').
'occupation' becomes 'ct' (I can't justify this - if you can you should give a lot more credence to this answer).
'ive' back-to-front is 'evi'.
'evi'+'ct'='EVICT'
'to give' is the link.
Can you help me to learn more?
(Other definitions for evict that I've seen before include "Civet (anag.)" , "Force to move out" , "Remove form house for non-payment" , "Expel from a dwelling" , "Throw out, expel" .)