Proper artist Tracey is short-term leader of the government (5,8)
'leader of the government' is the definition.
'prime minister' can be an answer for 'leader' (prime minister is a kind of leader). I am not certain of the 'of the government' bit.
'proper artist tracey is short-term' is the wordplay.
I cannot quite understand how this works, but
'proper' could be 'prim' (similar in meaning) and 'prim' is present in the answer.
'artist' could be 'emin' (I've seen this in other clues) and 'emin' is located in the answer.
'is' is within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for prime minister that I've seen before include "Leader 18 21", "Head of government", "Law once in UK", "North, for instance", "political leader".)