Tramp's son developed into fair person (9)
I believe the answer is:
sportsman
'fair person' is the definition.
'sportsman' can be an answer for 'person' (sportsman is a kind of person). I am unsure of the 'fair' bit.
'tramp's son developed' is the wordplay.
'developed' is an anagram indicator.
'tramps'+'son'='trampsson'
'trampsson' with letters rearranged gives 'SPORTSMAN'.
'into' is the link.
Can you help me to learn more?
(Other definitions for sportsman that I've seen before include "Chap aiming for game" , "Rower perhaps" , "player" , "Eg, athlete" , "He engages in physical games" .)