Extremely rare bike to use over again (7)
I believe the answer is:
recycle
'use over again' is the definition.
'recycle' can be an answer for 'use' (recycling is a kind of using). I'm not sure about the 'over again' bit.
'extremely rare bike' is the wordplay.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'bike' becomes 'cycle' (synonyms).
'rare' with its centre removed is 're'.
're'+'cycle'='RECYCLE'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for recycle that I've seen before include "Process for re-use" , "Convert waste to new usage" , "attempt to save the world?" , "Convert waste into form to be used again" , "Make new use of" .)