Doris occasionally wears jewellery that's hot (7)
I believe the answer is:
boiling
'hot' is the definition.
(similar in meaning)
'doris occasionally wears jewellery' is the wordplay.
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'wears' means one lot of letters goes inside another.
'jewellery' becomes 'bling' (informal term for jewellery).
The alternate letters of 'doris' are 'oi'.
'oi' put inside 'bling' is 'BOILING'.
'that's' is the link.
(Other definitions for boiling that I've seen before include "Seething" , "Extremely hot" .)