Coming at intervals in spring crocuses exceed daffodils at first (6)
I believe the answer is:
spaced
'coming at intervals' is the definition.
(spaced out in intervals)
'spring crocuses exceed daffodils at first' is the wordplay.
'spring' becomes 'spa' (spa can mean a mineral spring).
'at first' says to take the initial letters.
The first letters of 'crocuses exceed daffodils' is 'ced'.
'spa'+'ced'='SPACED'
'in' is the link.
(Other definitions for spaced that I've seen before include "Separated by gaps" , "set some distance apart" , "Placed at intervals" , "strung out" , "positioned at intervals" .)