Sticks up broken leg to avoid customs duty (7)
I believe the answer is:
smuggle
'avoid customs duty' is the definition.
I can't tell whether this defines the answer.
'sticks up broken leg' is the wordplay.
'sticks' becomes 'gums'.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'broken' indicates anagramming the letters.
'gums' reversed gives 'smug'.
'leg' is an anagram of 'gle'.
'smug'+'gle'='SMUGGLE'
'to' is the link.
Can you help me to learn more?
(Other definitions for smuggle that I've seen before include "Adherent of religion founded by Guru Nanak" , "Import illegally" , "boot-leg" , "traffic" , "Convey illegally" .)