America takes class line on moneylending (5)
I believe the answer is:
usury
'moneylending' is the definition.
(I've seen this before)
'america takes class line on' is the wordplay.
'america' becomes 'US' (United States).
'takes class' becomes 'u' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'line' becomes 'ry' (abbreviation for railway).
'on' means one lot of letters go next to another.
'us'+'u'+'ry'='USURY'
Can you help me to learn more?
(Other definitions for usury that I've seen before include "Loaning money at high interest" , "Extortionate moneylending" , "Taking excessive interest" , "Taking a lot of interest" , "Demanding excessive interest" .)