Lowers expectations from the start having left PM - see above (6)
I believe the answer is:
cattle
'lowers' is the definition.
(I've seen this before)
'expectations from the start having left pm see above' is the wordplay.
I cannot quite understand how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'left' could be 'l' (common abbreviation) and 'l' is found within the answer.
'see' could be 'c' (the word for the letter, according to Chambers) and 'c' is found in the answer.
The remaining letters 'at' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cattle that I've seen before include "Where it naturally lies (Latin)" , "Ruminant animals with horns and cloven feet" , "Lowers" , "Ruminants, often domesticated" , "Farm animals" .)