Very slow climbing lower down from peak (6)
I believe the answer is:
torpid
'very slow' is the definition.
(I've seen this before)
'climbing lower down from peak' is the wordplay.
'climbing' says the letters should be written in reverse (in a down clue, letters climb up).
'lower' becomes 'dip' (dip can mean to lower or go down).
'down from peak' becomes 'rot' (I can't explain this - if you can you should believe this answer much more).
'dip'+'rot'='diprot'
'diprot' back-to-front is 'TORPID'.
Can you help me to learn more?
(Other definitions for torpid that I've seen before include "Lethargic, sluggish" , "Sluggish and inactive" , "Conservative nearly given money to withhold article" , "Slow and apathetic" , "Inactive, dormant" .)