How can I make this arrow appear?

[Justastudent]

Hello,

Last time I could solve my pupil problem by linking the right pupil to the eyeball. But I cannot remember how I did that. 
Can someone please help me and explain how I can make this downward arrow appear again between the pupil and the eyeball? Thank You. 

[alank99101739]

select the layer then pick "create clipping mask" from the menus

[Justastudent]

Thank you very much!