Sportsman beginning to tacitly flatter hosts (7)
I believe the answer is:
eventer
'sportsman' is the definition.
(I've seen this before)
'beginning to tacitly flatter hosts' is the wordplay.
'beginning to' indicates taking the first letters.
'flatter' becomes 'evener' ('even' can be similar in meaning to 'flat').
'hosts' means one lot of letters goes inside another (inserted letters are welcomed or hosted).
The first letter of 'tacitly' is 't'.
't' going inside 'evener' is 'EVENTER'.
(Other definitions for eventer that I've seen before include "Rider in contests" , "Showjumper" , "Competing horse or rider" , "Competitive horse/rider" , "Jumper" .)