Fail to go to girl (4)
I believe the answer is:
miss
'girl' is the definition.
(term of address for an unmarried woman)
'fail to go to' is the wordplay.
'fail' becomes 'omit' (I've seen this before).
'go' indicates named letters should be taken away.
'to' becomes 'ss' (I can't justify this - if you can you should give a lot more credence to this answer).
'omit' with 'to' taken out is 'mi'.
'mi'+'ss'='MISS'
Can you help me to learn more?
(Other definitions for miss that I've seen before include "Fail to attend (event)" , "Don't hit" , "Feel the absence of" , "Young woman" , "Shoot over" .)