Lizard quickened again around mid-January (6)
I believe the answer is:
iguana
'lizard' is the definition.
(I know that iguana is a type of iguanid)
'quickened again around mid-january' is the wordplay.
'quickened again' becomes 'rebrisked' ('brisked' is an answer for 'quickened' so perhaps 'rebrisked' is OK for 'quickened again').
'around' means to look at the middle letters.
'mid january' becomes 'guana' (I can't justify this - if you can you should believe this answer much more).
The central letter of 'rebrisked' is 'i'.
'i'+'guana'='IGUANA'
Can you help me to learn more?
(Other definitions for iguana that I've seen before include "Lizard Darwin found in the Galapagos" , "Arboreal lizard of S America" , "Tropical American lizard" , "Could be a monitor" , "Something like a monitor" .)