Swelling crack disturbed here and there? (6)
I believe the answer is:
goitre
'swelling' is the definition.
(I've seen this before)
'crack disturbed here and there?' is the wordplay.
'crack' becomes 'go' (synonyms).
'here and there?' means one should take alternating letters (here and then can mean regularly).
The alternating letters of 'disturbed' are 'itre'.
'go'+'itre'='GOITRE'
(Other definitions for goitre that I've seen before include "Abnormally enlarged thyroid gland" , "Enlarged thyroid gland showing as neck swelling" , "Enlarged thyroid gland with swollen neck" .)