Offered to cross line for bit of grass (5)
I believe the answer is:
blade
'bit of grass' is the definition.
(blade of grass)
'offered to cross line' is the wordplay.
'offered' becomes 'bade' (I've seen this in another clue).
'to cross' means one lot of letters goes inside another.
'line' becomes 'l' (used when specifying particular lines from a poem).
'bade' going around 'l' is 'BLADE'.
'for' acts as a link.
(Other definitions for blade that I've seen before include "cutter" , "A knife, or a dashing fellow" , "See 24 Across" , "Leaf, of grass, say" , "Cutting part of grass?" .)