Uni led astray over principle of gallows humour (7)

I believe the answer is:

indulge

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'humour' is the definition.
(I know this)

'uni led astray over principle of gallows' is the wordplay.
'astray' is an anagram indicator.
'over' is an insertion indicator.
'principle of gallows' becomes 'g' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'uni'+'led'='uniled'
'uniled' anagrammed gives 'indule'.
'indule' enclosing 'g' is 'INDULGE'.

Can you help me to learn more?

(Other definitions for indulge that I've seen before include "Satisfy (an interest)" , "Coddle while eluding." , "Partake" , "take to the drink?" , "Allow person to have what he/she wishes" .)

I've seen this clue in The Independent.

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