Very dangerous to be out on one leg (4)
I believe the answer is:
limb
'one leg' is the definition.
(I've seen this before)
'very dangerous to be out on' is the wordplay.
'very dangerous' becomes 'lim' (I can't justify this - if you can you should give a lot more credence to this answer).
'out' means to remove the last letter.
'on' means one lot of letters go next to another.
'be' with its last letter removed is 'b'.
'lim'+'b'='LIMB'
Can you help me to learn more?
(Other definitions for limb that I've seen before include "Tentacle" , "Human's extension" , "Branch of a tree (risky to go out on)" , "as part of plane, say" , "Part of body or branch of tree" .)