Refusal to make room for just one little boy (6)
I believe the answer is:
denial
'refusal' is the definition.
(I know that refusal can be written as denial)
'room for just one little boy' is the wordplay.
'room' becomes 'den' (den is a kind of room).
'for' says to put letters next to each other.
'just one little boy' becomes 'ial' (I can't explain this - if you can you should give a lot more credence to this answer).
'den'+'ial'='DENIAL'
'to make' is the link.
Can you help me to learn more?
(Other definitions for denial that I've seen before include "Refusal, abnegation" , "Refusal to accept an unpalatable truth" , "Act of asserting that something alleged is not true" , "Refusal to admit painful truths" , "Rejection or refusal" .)