Stars reportedly cause irritation out of habit (5,4)
I believe the answer is:
great bear
'stars' is the definition.
(constellation Ursa Major)
'reportedly cause irritation out of habit' is the wordplay.
I cannot quite see how this works, but
'reportedly' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
'cause' could be 'bear' (bear is a kind of cause) and 'bear' is found in the answer.
The remaining letters 'grat' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for great bear that I've seen before include "'Large ursine in the heavens (5,4)'" , "Ursa Major" , "Plough constellation" , "Major stars" , "Large animal - same as 7" .)