Reveal (information) (7)
'reveal information' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for let on that I've seen before include "Pretend informally or permit to board" , "give the game away" , "Reveal information" , "Allow to board, or pretend" , "Tell me" .)
(Other definitions for divulge that I've seen before include "Disclose (a secret)" , "Communicate" , "Disclose, give away" , "Reveal as with information" , "Make known (a secret)" .)