Talk freely, giving the starting price away (5)
I believe the answer is:
spout
'talk freely' is the definition.
'spout' can be an answer for 'talk' (spout can informally mean to talk about something). I am not sure about the 'freely' bit.
'giving the starting price away' is the wordplay.
'giving' means one lot of letters go next to another.
'the starting price' becomes 'sp' (abbreviation in betting).
'away' becomes 'out' (similar in meaning).
'sp'+'out' is 'SPOUT'.
Can you help me to learn more?
(Other definitions for spout that I've seen before include "Gush" , "Speak in a declamatory way; pipe for liquid" , "Pontificate" , "Talk (rubbish); part of pot" , "Pouts beneath jet of liquid" .)