Blast, three raised model complaint! (9)
I believe the answer is:
gastritis
'complaint' is the definition.
(gastritis is a kind of disease)
'blast three raised model' is the wordplay.
'blast' becomes 'gas' (I've seen this in another clue).
'three' becomes 'tri' (prefix meaning 'three').
'raised' says the letters should be written in reverse (going up in a down clue).
'model' becomes 'sit' (e.g. for a painting).
'sit' in reverse letter order is 'tis'.
'gas'+'tri'+'tis'='GASTRITIS'
(Other definitions for gastritis that I've seen before include "medical problem" , "stomach upset" , "Stomach inflammation" , "stomach problem" , "Stomach complaint" .)