Looking sickly with a broken leg is just a trick! (6)
I believe the answer is:
wangle
'just a trick' is the definition.
I can't judge whether this defines the answer.
'looking sickly with a broken leg' is the wordplay.
'looking sickly' becomes 'wan' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'a broken' is an anagram indicator.
'leg' with letters rearranged gives 'gle'.
'wan'+'gle'='WANGLE'
'is' is the link.
Can you help me to learn more?
(Other definitions for wangle that I've seen before include "Obtain by being persuasive" , "Accomplish something by scheming or trickery" , "Use craft to get" , "Contrive to get for oneself" , "Finagle" .)