Teems as spring comes in (7)
I believe the answer is:
abounds
'teems' is the definition.
(I've seen this in another clue)
'as spring comes in' is the wordplay.
'spring' becomes 'bound' (synonyms).
'comes in' indicates putting letters inside.
'as' enclosing 'bound' is 'ABOUNDS'.
(Other definitions for abounds that I've seen before include "Is plentiful" , "Exists in large quantities" , "Exists in large numbers or amounts" , "Flourishes" , "Is all over the place" .)