Willow is more intimate, but not at first (5)
I believe the answer is:
osier
'willow' is the definition.
(I know that osier is a type of willow)
'more intimate but not at first' is the wordplay.
'more intimate' becomes 'cosier' (I've seen this in another clue).
'but not at first' means to remove the first letter.
'cosier' with its first letter taken off is 'OSIER'.
'is' is the link.
(Other definitions for osier that I've seen before include "Bit of tree" , "Willow growing shoots used in basketwork" , "Basket maker" , "Wood" , "Basket material" .)