Shark that’s spotted female is hot on trail (7)
I believe the answer is:
dogfish
'shark' is the definition.
(dogfish is a kind of shark)
'spotted female is hot on trail' is the wordplay.
'spotted female' becomes 'f' (abbreviation. I am not sure about the 'spotted' bit.**).
'hot' becomes 'h'.
'on' means one lot of letters go next to another.
'trail' becomes 'dog' ('dog' can be a synonym of 'trail').
'f'+'is'+'h'='fish'
'fish' put after 'dog' is 'DOGFISH'.
'that's' acts as a link.
(Other definitions for dogfish that I've seen before include "'Small shark, sounds canine (7)'" , "Nursehound" , "Small, edible shark" , "Restaurants call it rock salmon" .)