Climber is needing energy in repeated runs (5)
I believe the answer is:
riser
'climber' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'is needing energy in repeated runs' is the wordplay.
'needing' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mc2).
'in' is an insertion indicator.
'repeated' shows that letters should be duplicated.
'runs' becomes 'r' (cricket abbreviation).
'is'+'e'='ise'
'r' duplicated is 'rr'.
'ise' inserted within 'rr' is 'RISER'.
Can you help me to learn more?
(Other definitions for riser that I've seen before include "Section of flight" , "Bit of a step up?" , "Upright part of stair step" , "Person getting out of bed" , "I get up" .)