Around lake there's poor protection (7)
I believe the answer is:
Here is my best explanation:
'protection' is the definition.
(shelter is a kind of protection)
'around lake there's poor' is the subsidiary indication.
'around' is an insertion indicator.
'lake' becomes 'l'.
'poor' indicates an anagram.
'theres' is an anagram of 'sheter'.
'l' placed inside 'sheter' is 'shelter'.
(Other definitions for shelter that I've seen before include "Place offering protection", "Cover, protection", "Give protection", "Shield as from rain", "Protective structure", "'Refuge, cover (7)'", "Let hers go into shielded place", "Housing or haven", "Refuge, protection" and "harbour".)