Emotional rent boy's base (5)
I believe the answer is:
teary
'emotional' is the definition.
(likely to burst into tears)
'rent boy's base' is the wordplay.
'rent' becomes 'tear' (synonyms).
'boy's base' becomes 'y' (I can't justify this - if you can you should give a lot more credence to this answer).
'tear'+'y'='TEARY'
Can you help me to learn more?
(Other definitions for teary that I've seen before include "Crying" , "Weeping" , "Upset" , "Watery" , "Emotional" .)