...left in worried host lazing around (5)
I believe the answer is:
sloth
'lazing around' is the definition.
'sloth' can be an answer for 'lazing' (thesaurus). I am not certain of the 'around' bit.
'left in worried host' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' means one lot of letters goes inside another.
'worried' indicates anagramming the letters.
'host' anagrammed gives 'soth'.
'l' placed inside 'soth' is 'SLOTH'.
Can you help me to learn more?
(Other definitions for sloth that I've seen before include "Idleness" , "One hangs a lot" , "One of the seven deadly sins" , "one of a deadly collection" , "Arboreal creature" .)