Greeting oddly no use as line of approach (6)
I believe the answer is:
avenue
'line of approach' is the definition.
'avenue' can be an answer for 'approach' (both can refer to a road). I'm unsure of the 'line of' bit.
'greeting oddly no use' is the wordplay.
'greeting' becomes 'ave' (Latin greeting).
'oddly' means one should take alternating letters (letters in odd-numbered positions).
'no'+'use'='nouse'
The alternate letters of 'nouse' are 'nue'.
'ave'+'nue'='AVENUE'
'as' is the link.
Can you help me to learn more?
(Other definitions for avenue that I've seen before include "Tee-lined road" , "Way of approach" , "Wide, straight road" , "Wide street or road as in New York" , "Road leading to a house" .)