Stick leg out covering middle of rug (4)
I believe the answer is:
glue
'stick' is the definition.
(thesaurus)
'leg out covering middle of rug' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'covering' means one lot of letters goes inside another.
'middle of' says to take the centre.
The central letter of 'rug' is 'u'.
'leg' is an anagram of 'gle'.
'gle' enclosing 'u' is 'GLUE'.
(Other definitions for glue that I've seen before include "Stuff that sticks firmly" , "Sticker" , "Fixative" , "Bond" , "Paste" .)