Little tear perhaps left in tatty red top (7)
I believe the answer is:
droplet
'little tear' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'left in tatty red top' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'tatty' indicates an anagram (I've seen this in other clues).
'red'+'top'='redtop'
'redtop' is an anagram of 'dropet'.
'l' going inside 'dropet' is 'DROPLET'.
'perhaps' is the link.
Can you help me to learn more?
(Other definitions for droplet that I've seen before include "tiny amount of liquid" , "Small quantity of liquid" , "Small quantity of water, as in cloud" , "Small tear (of liquid)" , "Small globule" .)