Transmit the small limit (4)
I believe the answer is:
send
'transmit' is the definition.
(I know that send is a more specific form of the action the transmit)
'small limit' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'limit' becomes 'end' (I've seen this before).
's'+'end'='SEND'
'the' is the link.
(Other definitions for send that I've seen before include "Consign" , "Transmit; post" , "broadcast" , "Dispatch by post" , "Transport" .)